JPH1127690A - Television signal processing circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent degradation of subtitle resolution and cross color interference caused by Y / C separation. SOLUTION: A letter box determination signal of a letter box detection circuit 503 indicates that an input television signal is a letter box display formed image, and a subtitle detection circuit 5
When the caption determination signal of No. 04 indicates that there is a caption, the control signal generation circuit 101 generates a caption period control signal having a pulse indicating a caption period based on the video end position signal and the caption end position signal from the circuits 503 and 504. , Switch 102
And 103. During the non-caption period, switch 102
And 103 select the Y signal and the C signal from the Y / C separation circuit 502, respectively. During the caption period, switch 102
Denotes an input television signal, and the switch 103 selects a reference voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Y / C separating means for separating an input television signal into a luminance signal and a chrominance signal,
The present invention relates to a television signal processing circuit provided with a letterbox detecting means for detecting whether or not an input television signal is a video in a letterbox format, and a caption detecting means for detecting the presence or absence of a caption of the input television signal.

[0002]

2. Description of the Related Art In movie software or the like, there is a case where a subtitle is added to a lower non-image portion period in a letter box format image having a non-image portion of a black band image at the top and bottom as shown in FIG.
Current wide-aspect television receivers have a function of enlarging the display from the video start position to the subtitle end position so that the screen is full when such a television signal is input.

FIG. 5 shows a configuration example of such a wide aspect television receiver.

A television signal input from an input terminal 501 is converted into a Y / C separation circuit 502, a letterbox detection circuit 503, a subtitle detection circuit 504, and a vertical synchronization circuit 50.
5, is supplied to the horizontal synchronization circuit 506.

[0005] A Y / C separation circuit 502 extracts a chrominance signal (hereinafter, referred to as C signal) and a luminance signal (hereinafter, referred to as Y signal) from an input television signal. The Y signal and the C signal are supplied to wide aspect display means 509 via terminals 510 and 511, respectively.

A letterbox detection circuit 503 detects whether or not there are non-picture parts in the upper and lower portions of the input television signal, and determines whether the input television signal is a 4: 3 aspect ratio image or a letterbox format image. I do.

The letterbox detection circuit 503 outputs a letterbox determination signal indicating whether or not the image is a letterbox image, a video start position signal indicating the video start position of the main image portion video, and a video end position signal indicating the video end position. Vertical deflection circuit 512 via terminals 512, 516 and 513, respectively.
Output to

[0008] A subtitle detection circuit 504 detects whether or not there is a subtitle in the lower non-picture part period of the letterbox format television signal, and a subtitle determination signal indicating the presence or absence of the subtitle, and a subtitle end position indicating the subtitle end position. The signal is applied to terminal 514, respectively.
The signal is output to the vertical deflection circuit 512 via 515.

A vertical synchronization circuit 505 reproduces a vertical synchronization signal from an input television signal. The reproduced vertical synchronization signal is output to the vertical deflection circuit 507.

The horizontal synchronization circuit 506 reproduces a horizontal synchronization signal from an input television signal. The reproduced horizontal synchronization signal is output to the horizontal deflection reproduction circuit 508.

A vertical deflection circuit 507 generates a vertical scanning signal for deflecting the scanning line of the wide aspect display means 509 in the vertical direction from the vertical synchronization signal, and outputs the signal to the wide aspect display means 509.

A vertical deflection circuit 507 receives a letterbox determination signal, a video start position signal, a video end position signal, a caption determination signal, and a caption end position signal, and determines that the letterbox determination signal is a letterbox format image. When shown, the vertical scanning signal is controlled so that the main image portion video period is enlarged and displayed.

If the letter box determination signal indicates that the image is a letter box format image and the subtitle determination signal indicates that subtitles are present, the image from the video start position to the subtitle end position is enlarged and displayed on the wide aspect display means 509. The vertical scanning signal is controlled as described above.

The horizontal deflection circuit 508 generates a horizontal scanning signal for deflecting the scanning lines of the wide aspect display means 509 in the horizontal direction from the horizontal synchronization signal, and outputs the signal to the wide aspect display means 509.

The wide aspect display means 509 scans the Y signal and the C signal with the vertical scanning signal and the horizontal scanning signal, and displays them on the screen.

As described above, the wide-aspect television receiver is constructed, and the screen is enlarged and displayed according to the input television signal.

[0017]

As a method of displaying subtitles in movie software or the like, as shown in FIG. 6, subtitles are superimposed on the lower non-picture portion, the background is black, and the subtitles are displayed in white characters. .
That is, the caption period is composed of only the luminance signal component. The edge portion of the caption changes sharply from the black level to the white level, and includes a horizontal high frequency component and a vertical high frequency component. On the other hand, as is well known in the NTSC television signal, the color signal is superimposed on the horizontal high-frequency band and the vertical high-frequency band.

Therefore, when the subtitle portion is Y / C separated, cross-color interference in which the luminance signal leaks into the chrominance signal may occur at the edge portion of the subtitle. Especially Y /
When performing C separation, cross-color interference is likely to occur. In addition, when a luminance signal is extracted by removing a color signal from a television signal, the subtitle resolution is deteriorated due to the erroneous extraction of a subtitle edge portion as a color signal.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a television signal processing circuit for preventing the subtitle resolution degradation and cross-color interference caused by Y / C separation.

[0020]

[Means for Solving the Problems]

(First configuration example) A luminance / color signal separating means for inputting a television signal of a letterbox display format image and separating the signal into a luminance signal and a chrominance signal, and the input television signal is a letterbox display format image A television signal processing circuit comprising: a letterbox image detecting means for detecting whether or not the input television signal; and a subtitle detecting means for detecting whether or not a subtitle exists in a non-picture portion of the input television signal. First selecting means for selecting a television signal and the luminance signal, second selecting means for selecting an arbitrary fixed value and the color signal, an output of the letterbox image detecting means, and the subtitle detecting means From the output of the input television signal, a period of the input television signal that does not include the subtitles and a period of the input television signal that includes the subtitles are detected. The period included subtitles items,
The first selection unit selects the input television signal, the second selection unit selects an arbitrary fixed value, and the period of the input television signal that does not include the subtitle is the first selection. The means selects the luminance signal, and the second selecting means includes control means for controlling to select the color signal.

(Second Configuration Example) First and second luminance / color separating a luminance signal and a chrominance signal by inputting a television signal in which a caption is superimposed on a non-picture portion in a letterbox display format image A signal separation unit, a letterbox image detection unit that detects that the input television signal is a letterbox format image, and a subtitle detection unit that detects subtitles present in a non-picture portion of the input television signal. A television signal processing circuit provided with a selector for selecting the output of the first luminance / color signal separating means, the output of the second luminance / color signal separating means, and the output of the letterbox image detecting means. From the output of the subtitle detection means, a period of the input television signal that does not include the subtitle and a period of the input television signal that includes the subtitle are detected. The selecting means selects the output of the second luminance / color signal separating means during a period in which the caption of the vision signal is included, and the first luminance in a period in which the subtitle of the input television signal is not included. Control means for controlling the selection of the output of the color signal separation means.

(Third Configuration Example) A letterbox image detecting means for detecting whether or not an input television signal is a letterbox display format image, and a subtitle exists in a non-picture portion of the input television signal. Subtitle detecting means for detecting whether or not the output of the letterbox image detecting means and the output of the subtitle detecting means include a period in which no subtitle including the video period of the input television signal is included and the subtitle is included. And a vertical filter for extracting a component near a vertical frequency band of a color signal from the input television signal, and a first bandwidth A for band-limiting an output of the vertical filter in a horizontal direction. And a second water having a second bandwidth B (A> B) for horizontally band limiting the output of the vertical filter. When a control signal indicating a period during which the subtitle is not included is supplied from the bandpass filter and the control unit, the output of the first horizontal bandpass filter is selected, and the subtitle is included from the control unit. Selecting means for selecting an output of the second horizontal bandpass filter when a control signal indicating a period is supplied; and subtracting means for subtracting an output of the selection means from the input television signal. Features.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a block diagram of a television signal processing circuit according to a first embodiment of the present invention. In the present embodiment, only the portion surrounded by a dotted line in the conventional example shown in FIG. 5 is changed. FIG. 5 shows a conventional vertical synchronization circuit 5.
From 05, the wide aspect display means 509 is the same and the description is omitted. Also in the present embodiment, the same reference numerals are given to portions having the same function among the portions surrounded by dotted lines in the conventional example, and the description thereof is omitted.
Hereinafter, the first embodiment will be described.

A television signal input from an input terminal 501 is supplied to a Y / C separation circuit 502, a letterbox detection circuit 503, and a subtitle detection circuit 504, and is also supplied to an input terminal 102b of the switch 102.

The letter box determination signal and the video end position signal output from the letter box detection circuit 503 are supplied to output terminals 512 and 513, respectively.
It is also supplied to the control signal generation circuit 101.

A caption determination signal and a caption end position signal output from the caption detection circuit 504 are output from an output terminal 51, respectively.
4 and 515 and a control signal generation circuit 1
01 is also supplied.

The control signal generation circuit 101 includes a switch 10
2. Output a caption period control signal for controlling the switch 103. The subtitle period control signal indicates that the letterbox determination signal is a letterbox display formed image and, when the subtitle determination signal indicates that subtitles are present, a video end position signal and a subtitle end position signal as shown in FIG. 3 shows a signal waveform representing a caption period.

That is, the letter box determination signal is 4: 3
When the image indicates an aspect ratio image, or when the subtitle determination signal indicates no subtitle, the switches 102, 1
03 shows signal waveforms in which the selectors 102a and 103a select the input terminals 102c and 103c to which the Y and C signals output from the Y / C separation circuit 502 are supplied, respectively.

A selector 102a of the switch 102 selects an input terminal 102c to which a Y signal is supplied during a non-subtitle period including a main picture portion video period, based on a subtitle period control signal output from the control signal generation circuit 101. During the caption period, the input terminal 102b to which the input television signal from the input terminal 501 is supplied is selected. The output of switch 102 is provided to terminal 510.

Therefore, the main picture portion video period is the normal Y /
The C signal is separated to extract the Y signal. During the caption period, the Y / C separation is not performed, and the input television signal is output to the output terminal 51 as it is.
Output to 0. Therefore, it is possible to prevent the resolution of the subtitle portion from deteriorating due to the conventional Y / C separation.

On the other hand, the selector 103a of the switch 103, like the switch 102, selects the input terminal 103c to which the C signal is supplied during the non-caption period including the main picture portion video period by the caption period control signal, and During the period, the input terminal 103b to which the reference potential is supplied is selected. Switch 103
Is supplied to an output terminal 511.

Therefore, the main picture portion video period is the same as the normal Y
The C signal is extracted by performing the / C separation, and the reference potential is output to the output terminal 511 during the caption period. Therefore, it is possible to prevent the problem that the cross color interference of the subtitle portion occurs due to the Y / C separation as in the related art.

As described above, it is possible to prevent the subtitle resolution degradation and the cross color interference caused by the conventional Y / C separation, and to solve the conventional problems.

(Second Embodiment) FIG. 2 shows a configuration diagram of a television signal processing circuit according to a second embodiment of the present invention.

In the first embodiment, the subtitle period is Y / C
The separation operation is stopped, the input television signal is output as a Y signal, and the C signal is used as a reference potential, thereby preventing resolution degradation of subtitles and cross color interference.

However, in rare cases, there are cases where the subtitles are colored or where the background portion of the subtitles in the non-image portion is colored. When such a television signal is input, dot interference in which the C signal leaks into the Y signal occurs in the first embodiment.

The second embodiment solves such a problem. In FIG. 2, blocks having the same functions as those in the conventional example and the first embodiment are given the same numbers, and descriptions thereof are omitted. Hereinafter, a second embodiment will be described.

The C signal output from the Y / C separation circuit 502 is supplied to the input terminal 103c of the switch 103 and also to the colorless detection circuit 201.

The video end position signal output from the letterbox detection circuit 503 is supplied to the output terminal 513 and also to the colorless detection circuit 201.

The subtitle end position signal output from the subtitle detection circuit 504 is supplied to an output terminal 515,
It is also supplied to the colorless detection circuit 201.

The colorless detection circuit 201 detects the presence or absence of a color component during a subtitle period from a video end position signal, a subtitle end position signal, and a C signal, and generates a colorless judgment signal indicating the presence or absence of a color component. Output to the circuit 202.

The C signal contains, in addition to the color component, a cross color component at the edge of the caption during the caption period. For example,
The color components have an inverted phase relationship between frames. If there is a cross color component at the edge of the subtitle, the subtitle portion is a still image, so the frames have the same phase, so it is determined whether or not it is a color component. it can. Further, if the line components are also color components, the lines have an inverted phase relationship, so that it is possible to determine whether or not they are color components.

Therefore, the presence or absence of a color component can be detected by detecting the correlation between frames and between lines.

The control signal generation circuit 202 is obtained by adding the presence or absence of a color component based on the color absence determination signal to the control signal generation circuit 101 of the first embodiment. The letter box determination signal indicates that the image is a letter box display formed image,
When the caption determination signal indicates that there is a caption and the colorless determination signal indicates that there is no color component, as in the first embodiment,
A subtitle period control signal indicating a subtitle period as shown in FIG. 6 is output.

When the letter box determination signal indicates that the image is a 4: 3 aspect ratio image, when the subtitle determination signal indicates that there is no subtitle, or when the colorless determination signal indicates that there is a color component, the switches 102 and 103 are used. Of the Y / C separation circuit 502
Input terminal 102c to which a Y signal and a C signal from
A subtitle period control signal for selecting 103c is output.

As described above, in the second embodiment, in addition to the first embodiment, when there is no color component in the subtitle period, the same operation as in the first embodiment is performed. Problem can be solved.

When there is a color in the subtitle portion of the subtitle period or when a color component exists in the background portion, the Y / C separation process is also performed in the subtitle period in the same manner as in the prior art, so that the first embodiment is not limited. The problem of dot disturbance in which the generated C signal leaks into the Y signal can be solved.

(Third Embodiment) FIG. 3 shows a configuration diagram of a television signal processing circuit according to a third embodiment of the present invention.

FIG. 3 shows an example in which motion adaptive three-dimensional Y / C separation is used in the Y / C separation processing.

In the motion adaptive three-dimensional Y / C separation, a luminance signal (hereinafter, referred to as a still image Y signal) and a color signal (hereinafter, referred to as a still image C signal) are extracted by inter-frame or inter-field operation processing. A C-separation and a two-dimensional Y / C separation for extracting a luminance signal (hereinafter, referred to as a moving image Y signal) and a color signal (hereinafter, referred to as a moving image C signal) by an intra-frame operation process are provided.

The Y / C separation process extracts the amount of motion between frames or fields by motion detection, and mixes the three-dimensional Y / C separated output and the two-dimensional Y / C separated output according to the amount of motion. .

Movement of letterbox image with subtitles to motion adaptation 3
When the dimensional Y / C separation is performed, since the subtitle period is a still image, a three-dimensional Y / C separation process is performed. When the subtitle portion is subjected to the three-dimensional Y / C separation processing, the operation is performed between frames or between fields, so that cross-color interference and degradation of subtitle resolution do not occur.

However, even if the image is a still image in the motion detection process due to the influence of noise or the like, there is a case where the motion is erroneously detected and the two-dimensional Y / C separation process is performed. In the two-dimensional Y / C separation, the horizontal high-frequency component is extracted as a C signal. Therefore, when the horizontal high-frequency component is included in the subtitle portion, cross-color interference as described in the related art is used. Problems occur.

In the third embodiment, the conventional problems are improved by reducing malfunctions caused by the motion detection. Hereinafter, a third embodiment will be described. 3, blocks having the same functions as those of the conventional example of FIG. 5 and the first embodiment of FIG.

The television signal input from the input terminal 501 is supplied to a two-dimensional Y / C separation 301, a three-dimensional Y / C separation 302, a motion detection circuit 303, a letterbox detection circuit 503, and a caption detection circuit 504. .

The two-dimensional Y / C separation circuit 301 performs intra-frame Y / C separation processing by inter-line operation or intra-line operation, and extracts a moving image Y signal and a moving image C signal.

The three-dimensional Y / C separation circuit 302 performs inter-frame or inter-field Y / C separation processing by inter-frame or inter-field operation processing, and extracts a still image Y signal and a still image C signal.

The motion detection circuit 303 performs an inter-frame or inter-field operation process, detects a motion component between frames or between fields, and outputs a motion signal indicating the amount of motion between frames or between fields to the mixers 304, 30.
5 respectively.

The motion detection circuit 303 switches the motion detection operation between the non-caption period and the caption period according to the caption period control signal output from the control signal generation circuit 101.

FIG. 7 illustrates a specific example of the motion detection circuit 303 according to the third embodiment. FIG. 7 shows an example of an inter-frame motion detection circuit for detecting the inter-frame motion amount.

Here, the relationship between the mixers 304 and 305 and the motion signals used for their control will be described.

Since the characteristics are greatly different between the three-dimensional Y / C separation and the two-dimensional Y / C separation, for example, when the motion signal is controlled as a binary signal, the switching instant becomes visually unnatural. . Therefore, when the movement is small, the still image Y
The unnaturalness is reduced by mixing the signal and the moving image Y signal, and the still image C signal and the moving image C signal according to the motion signal.

Here, a description will be given assuming that the motion signal supplied to the mixers 304 and 305 is represented by 3 bits.
An input television signal is supplied from a terminal 306 to an addition terminal of a one-frame delay unit 701 and a subtractor 702.

In the one-frame delay unit 701, the input television signal is delayed by one frame period and supplied to the subtraction terminal of the subtractor 702.

The subtractor 702 performs a difference calculation process between the input television signal and the input television signal delayed by one frame, and supplies a difference signal between one frame to the horizontal LPF 703.

If the input television signal is a still image with only the Y signal component, the difference signal between one frame is "0",
In the case of a moving image, a motion component corresponding to the motion is included in the one-frame difference signal. As is well known in the NTSC system, the C signal has an inverted phase relationship between one frame, so the one-frame difference signal also includes the C signal.

The horizontal LPF 703 removes the horizontal high-frequency component where the C signal exists, and extracts the motion component in the horizontal low frequency. The output of the horizontal LPF 703 is supplied to an absolute value circuit 704.

In the absolute value circuit 704, the horizontal LPF 703
The absolute value of the output is converted and supplied to the nonlinear processing circuit 705.

The non-linear processing circuit 705 performs non-linear arithmetic processing on the absolute value-converted difference signal between one frame, for example, as shown by a dotted line in FIG. 9, and outputs a 3-bit motion signal.

In FIG. 9, the horizontal axis represents the value of the input signal, and the vertical axis represents the value of the output signal. The output becomes 0 until the input is a1, and the mixers 304 and 305 output the still image Y signal,
Only the still image C signal is output. The input level exceeds a1,
Until a2 is reached, the ratio increases to 1, 2,... 6, and the ratio of the moving image Y signal and the moving image C signal increases as compared with the still image Y signal and the still image C signal. When the input level exceeds a2, the output becomes 7, and only the moving image Y signal and the moving image C signal are output from the mixers 304 and 305, respectively.

The output of the non-linear processing circuit 705 is
06.

The switch 706 is switched by a caption period control signal input from a terminal 307. When the caption period control signal indicates a non-caption period, the non-linear processing circuit 7
05 is selected and output to the terminal 308.

When the subtitle period control signal indicates the subtitle period, “0” is selected and output to the terminal 308.

Accordingly, the motion detection circuit 303 outputs a motion signal according to the amount of motion between frames so as to perform motion adaptive three-dimensional Y / C separation during the non-caption period.
The mixers 304 and 305 are controlled so as to be in a complete still image state in which only the still image Y signal and the still image C signal are output.

The mixer 304 mixes the moving image Y signal output from the two-dimensional Y / C separation circuit 301 and the still image Y signal output from the three-dimensional Y / C separation circuit 302 according to the motion signal. . The output of the mixer 304 is output from the output terminal 51.
0 is supplied.

The mixer 305 mixes the moving image C signal output from the two-dimensional Y / C separation circuit 301 and the still image C signal output from the three-dimensional Y / C separation circuit 302 according to the motion signal. . The output of mixer 305 is output terminal 511
Supplied to

As described above, in the third embodiment, the motion detection operation is switched between the non-subtitle period and the subtitle period, and the still images Y and C are output from the mixers 304 and 305 during the subtitle period.
It outputs a motion signal as output by a signal. Therefore, the problem that the motion detection circuit malfunctions due to noise can be solved by forcibly performing the three-dimensional Y / C separation processing during the caption period. Therefore, it is possible to solve the conventional problems of cross color interference and subtitle resolution degradation.

(Fourth Embodiment) FIG. 8 shows a configuration diagram of a motion detection circuit used in a television signal processing circuit according to a fourth embodiment of the present invention.

FIG. 8 shows an embodiment according to another configuration of the third embodiment shown in FIG.

In the third embodiment, the motion adaptive three-dimensional Y
The / C separation is forcibly made three-dimensional Y / C separation during the caption period to solve the problem of cross-color interference and the malfunction of the motion detection circuit.

However, in the case where the subtitles scroll from right to left as viewed on the screen, that is, in the case of a moving image, subtitles may occur because motion adaptive processing is not performed.

The fourth embodiment solves the problem of the related art and the problem of the third embodiment. Hereinafter, a fourth embodiment will be described. The fourth embodiment differs only in the configuration of the motion detection circuit 303 shown in FIG. 3, and the other blocks are the same. 8, blocks having the same functions as those in the third embodiment shown in FIG. 7 are assigned the same numbers, and descriptions thereof are omitted.

The output of the absolute value circuit 704 is supplied to a non-linear circuit 705 and a non-linear circuit 801.
Is also supplied.

The nonlinear processing circuit 801 performs nonlinear processing on the absolute value-converted difference signal between one frame and outputs a 3-bit motion signal, similarly to the nonlinear processing circuit 705.

An example of a characteristic diagram of the nonlinear processing circuit 801 is as follows.
This is shown by the solid line in FIG. Here, the characteristics are similar to those of the non-linear processing circuit 705 shown by the dotted line in FIG. 9, and the output becomes 0 until the input reaches b1, and the input level exceeds b1 until the input level reaches b2, and so on. It goes up with 6. When the input level becomes equal to or more than b2, the output is set to 7. At this time, there is a relationship of a1 <b1, a2 <b2.

Similarly to the non-linear processing circuit 705 described in the third embodiment, the mixers 304 and 305 in FIG. 3 use the still image Y signal and the still image until the input level of the non-linear processing circuit 801 is up to b1. Outputs only the C signal. The input level exceeds b1 and rises to 1, 2,... 6 until it reaches b2.
The ratio of the signal and the moving image C signal increases. When the input level exceeds b2, the output becomes 7, and only the moving image Y signal and the moving image C signal are output from the mixers 304 and 305, respectively.
Output from Since the relations a1 <b1 and a2 <b2 are satisfied, the non-linear processing circuit 801 is
In comparison with the case of the image data 05, the area for processing the still image becomes wider.

The switch 802 is switched by a subtitle period control signal input from a terminal 307. When the caption period control signal indicates a non-caption period, the non-linear processing circuit 7
05 is selected and output to the terminal 308. When the subtitle period control signal indicates the subtitle period, the non-linear processing circuit 801
The output is selected and output to the terminal 308. Therefore, the detection sensitivity of the motion amount of the motion detection circuit 303 can be reduced in the subtitle period as compared with the non-subtitle period.

As described above, in the fourth embodiment, the sensitivity of detecting a motion component is lower in the subtitle period than in the main image portion video period, so that three-dimensional Y / C separation processing is easily performed. As a result, similar to the third embodiment, it is possible to solve the conventional problems of cross color interference and subtitle resolution degradation.

The problem that occurs in the third embodiment when subtitles of a moving image such as scrolling in the horizontal direction are input can also be solved by performing the motion detection process.

In the subtitle period, the background is at the black level and the subtitle is at the white level. Since the level difference between the background and the subtitle is high, the level of the detected motion component is also high. Therefore, even if the sensitivity of the motion detection is reduced during the caption period, the motion component can be sufficiently detected.

(Fifth Embodiment) FIG. 4 shows a configuration diagram of a television signal processing circuit according to a fifth embodiment of the present invention.

FIG. 4 shows an example in which two-dimensional Y / C separation for extracting a Y signal and a C signal by intra-frame operation processing is used for the Y / C separation processing. In the fifth embodiment, as in the second embodiment, when the subtitles are colored in the first embodiment or the non-image portions are colored, dot interference occurs. To solve the problem.

Hereinafter, a fifth embodiment will be described. In FIG. 4, blocks having the same functions as those of the conventional example of FIG. 5 and the first embodiment of FIG.

The television signal input from the input terminal 501 is supplied to a letterbox detection circuit 503, a subtitle detection circuit 504, a vertical BPF 401, and an addition terminal of a subtractor 405.

The vertical BPF 401 limits the band of the input television signal in the vertical direction, and extracts a component near the vertical frequency band of the C signal. The output of the vertical BPF 401 is supplied to horizontal BPFs 402 and 403.

In the horizontal BPF 402, the vertical BPF 401
The output is band-limited in the horizontal direction to extract the C signal component. The output of the horizontal BPF 402 is supplied to an input terminal 404b of the switch 404.

The horizontal BPF 403 is a band-pass filter having a bandwidth narrower than that of the horizontal BPF 402.
As in 02, the output of the vertical BPF 401 is band-limited in the horizontal direction to extract the C signal component. The output of the horizontal BPF 403 is supplied to an input terminal 404c of the switch 404.

FIG. 10 shows an example of a characteristic diagram of the horizontal BPFs 402 and 403. In FIG. The characteristics of the horizontal BPF 402 are indicated by dotted lines, and the characteristics of the horizontal BPF 403 are indicated by solid lines.

As shown in FIG. 10, like the horizontal BPF 402, the horizontal BPF 403 is a filter having a center frequency of 3.58 [MHz] of the color subcarrier frequency of the NTSC system.
The bandwidth is narrower than that of the horizontal BPF 402. When the letterbox image with captions shown in FIG. 6 is input, the horizontal BPF 402 has a wide bandwidth, so that the edge of the captions in the caption period is easily erroneously extracted as a C signal.
In contrast, the horizontal BPF 403 has a narrow bandwidth,
As compared with the horizontal BPF 402, the edge portion of the caption during the caption period is less likely to be erroneously extracted as the C signal.

The selector 404a of the switch 404 selects the input terminal 404b to which the output of the horizontal BPF 402 is supplied when the subtitle period control signal output from the control signal generation circuit 101 indicates a non-subtitle period, and When indicating the period, the input terminal 404c to which the output of the horizontal BPF 403 is supplied is selected. The output of the switch 404 is supplied to a subtraction end of the subtractor 405 and an output terminal 511.

Therefore, the vertical BPF 4
01, the C signal is extracted by the horizontal BPF 402, and the C signal is extracted by the vertical BPF 401 and the horizontal 403 during the caption period.

The subtracter 405 subtracts the C signal from the input television signal to extract a Y signal. Subtractor 305
The output is supplied to an output terminal 510.

FIG. 11 shows Y output from subtractor 405.
FIG. 3 shows a horizontal frequency characteristic diagram of a signal. In this figure, the horizontal frequency characteristic of the Y signal when the vertical frequency of the input television signal is 525/4 [lph] is shown, the dotted line is the horizontal frequency characteristic of the Y signal in the non-caption period, and the solid line is the Y signal in the subtitle period. The horizontal frequency characteristics of

Since the horizontal BPFs 402 and 403 each have characteristics as shown in FIG. 10, the characteristics of the Y signal extracted by the subtracter 405 are as shown in FIG.

In the case of a caption period, the Y signal has characteristics as shown by a solid line, and the area for extracting the caption as a Y signal is widened. Therefore, during the subtitle period, the horizontal B for extracting the C signal is used.
By reducing the bandwidth of the PF, it is possible to reduce the degradation of the resolution of the caption.

As described above, in the fifth embodiment, the characteristics of the horizontal BPF are switched between the non-caption period and the caption period, and the C signal is extracted by the band-pass filter having a band narrower than the non-caption period during the caption period. I do. As a result, the conventional problem of cross color interference at the edge of the subtitle can be improved. Further, since the frequency band to be extracted as the Y signal is widened, it is possible to improve the conventional degradation of the caption resolution.

Further, since the Y / C separation process is performed even when a color component exists in the subtitle period, the problem of dot disturbance occurring in the subtitle period generated in the first embodiment can be solved. .

[0108] Instead of the vertical BPF 401, the same effect can be obtained by a logical filter that detects a pattern in the vertical direction and extracts a component near the vertical frequency band of the C signal.

As described in the first to fifth embodiments, according to the television signal processing circuit of the present invention, it is possible to solve the conventional problems.

The non-caption period may be from the caption start position to the caption end position instead of the video end position.

In the present invention, when subtitles are detected, Y
Although the / C separation processing operation is switched, a similar effect can be obtained only with the output of letterbox detection. For example, the same effect can be obtained by switching the Y / C separation processing operation during the lower non-image portion period after the video end position regardless of the presence or absence of subtitles.

[0112]

As described above, according to the television signal processing circuit of the present invention, it is possible to prevent the cross color interference and the degradation of the resolution of the subtitles which occur at the edge of the subtitles existing in the non-picture part of the letterbox image. It is possible to reduce.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of a television signal processing circuit of the present invention.

FIG. 2 is a configuration diagram of a television signal processing circuit according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of a television signal processing circuit of the present invention.

FIG. 4 is a configuration diagram of a fifth embodiment of the television signal processing circuit of the present invention.

FIG. 5 is a configuration diagram of a conventional wide aspect television receiver.

FIG. 6 is a diagram illustrating an example of a letterbox image with subtitles.

FIG. 7 is a block diagram illustrating a specific example of a motion detection circuit 303 in FIG. 3;

FIG. 8 is a configuration block diagram of a motion detection circuit used in a fourth embodiment of the television signal processing circuit of the present invention.

FIG. 9 is a characteristic diagram of the non-linear processing circuits 705 and 801 used in FIGS. 7 and 8;

10 shows a horizontal BPF 402 and a horizontal BPF 403 in FIG.
FIG. 9 is a characteristic diagram of an example of FIG.

11 is a characteristic diagram of a Y signal output from a subtractor 405 in FIG.

[Explanation of symbols]

502: Y / C separation circuit, 503: letter box detection circuit, 504: subtitle detection circuit, 505 ...
.Vertical synchronization circuit, 506... Horizontal synchronization circuit, 507 vertical deflection circuit, 508... Horizontal deflection circuit, 509.
Wide aspect display means, 101, 202 ... control signal generation circuit, 102, 103 ... switch, 201
... colorless detection circuit, 301 ... two-dimensional Y / C separation circuit, 302 ... three-dimensional Y / C separation circuit, 303 ...
・ Motion detection circuit, 304, 305 ・ ・ ・ Mixer, 40
1, vertical BPF (bandpass filter), 402
403: horizontal BPF (bandpass filter), 40
4 ... switch, 701 ... 1 frame delay unit, 7
02: subtractor, 703: horizontal LPF (low-pass filter), 704: absolute value conversion circuit, 705, 8
01 ... Non-linear processing circuit.

Claims (6)

[Claims] 1. A television signal of a letter-box display format image is inputted, and a luminance / luminance signal for separating a luminance signal and a chrominance signal is provided.
A color signal separating unit; a letterbox image detecting unit that detects whether the input television signal is a letterbox display format image; and whether a subtitle exists in a non-image portion of the input television signal. A television signal processing circuit comprising: a subtitle detection unit for detecting whether the input television signal and the luminance signal are selected; and selecting an arbitrary fixed value and the color signal. A second selecting unit, a period of the input television signal that does not include the subtitles, and a period that includes the subtitles of the input television signal, based on the output of the letterbox image detecting unit and the output of the subtitle detecting unit. During the period during which the subtitles of the input television signal are included, the first selection means selects the input television signal and performs the second selection. The means selects an arbitrary fixed value, and during a period not including the subtitle of the input television signal, the first selecting means selects the luminance signal, and the second selecting means selects the color signal. A television signal processing circuit, comprising: control means for controlling the television signal processing. 2. The apparatus according to claim 1, wherein the control unit includes a color detection unit that detects the presence or absence of a color signal component during a subtitle period of a non-picture portion of the input television signal. When detecting that the image is an image, and when the subtitle detection means detects the presence of subtitles in a non-picture portion of the input television signal, and when the color detection means detects that there is no color signal component, A control signal indicating a period from the end position of the video period of the input television signal to the end position of the subtitle period is output, and the control signal causes the first selecting means to select the input television signal, 2. The television signal processing circuit according to claim 1, wherein said second selection means selects said arbitrary fixed value. 3. A first and second luminance / color signal separation means for inputting a television signal in which a caption is superimposed on a non-image portion in a letterbox display format image and separating a luminance signal and a chrominance signal, A television signal comprising: a letterbox image detecting means for detecting that the input television signal is a letterbox format image; and a caption detecting means for detecting captions present in a non-picture portion of the input television signal. A processing circuit for selecting the output of the first luminance / color signal separation means and the output of the second luminance / color signal separation means; the output of the letterbox image detection means and the output of the subtitle detection means From the output, a period of the input television signal not including the subtitle and a period of the input television signal including the subtitle are detected, and the input television signal is detected. The selecting means selects the output of the second luminance / color signal separating means during the period in which the subtitle is included, and the first luminance / color in the period in which the subtitle of the input television signal is not included. A television signal processing circuit, comprising: control means for controlling an output of the signal separation means to be selected. 4. The control means detects that the letterbox image detecting means is a letterbox display format image, and the caption detecting means detects the presence of a caption in a non-picture portion of the input television signal. Then, a control signal indicating a period from the end position of the video period of the input television signal to the end position of the subtitle period is output. 4. The television signal processing circuit according to claim 3, wherein an output of the means is selected. 5. The motion-adaptive three-dimensional luminance / color signal, comprising: a first luminance / color signal separation unit that detects a motion amount of a video between frames or fields of the input television signal. A second luminance / color signal separating unit, which forms a part of the motion three-dimensional luminance / color signal separating unit, and converts the input television signal into a luminance signal by an inter-frame or inter-field operation. 4. The television signal processing circuit according to claim 3, wherein the television signal processing circuit is a three-dimensional luminance / color signal separation unit that separates color signals. 6. A letterbox image detecting means for detecting whether or not an input television signal is a letterbox display format image, and detecting whether or not a subtitle exists in a non-picture portion of the input television signal. Detecting a period in which no subtitle including the video period of the input television signal is included and a period in which the subtitle is included from the output of the letterbox image detecting unit and the output of the subtitle detecting unit. A vertical filter for extracting a component near a vertical frequency band of a color signal from the input television signal; and a first filter for horizontally band-limiting an output of the vertical filter.
A first horizontal bandpass filter having a bandwidth A, and a second bandlimiting the output of the vertical filter in the horizontal direction.
A second horizontal bandpass filter having a bandwidth B (A> B), and a first horizontal bandpass filter when a control signal indicating a period in which the subtitle is not included is supplied from the control means. Selecting an output of a filter, and when a control signal indicating a period in which the subtitle is included is supplied from the control means, selecting means for selecting an output of the second horizontal bandpass filter; and A television signal processing circuit, comprising: a subtraction unit for subtracting an output of the selection unit.